1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver 4 * 5 * Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com> 6 * 7 * Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf 8 * 9 * SPI interface connections 10 * 11 * SPI MAXIM 12 * Master Direction MAX1117/8/9 13 * ------ --------- ----------- 14 * nCS --> CNVST 15 * SCK --> SCLK 16 * MISO <-- DOUT 17 * ------ --------- ----------- 18 */ 19 20 #include <linux/module.h> 21 #include <linux/mod_devicetable.h> 22 #include <linux/spi/spi.h> 23 #include <linux/iio/iio.h> 24 #include <linux/iio/buffer.h> 25 #include <linux/iio/triggered_buffer.h> 26 #include <linux/iio/trigger_consumer.h> 27 #include <linux/regulator/consumer.h> 28 29 enum max1118_id { 30 max1117, 31 max1118, 32 max1119, 33 }; 34 35 struct max1118 { 36 struct spi_device *spi; 37 struct mutex lock; 38 struct regulator *reg; 39 /* Ensure natural alignment of buffer elements */ 40 struct { 41 u8 channels[2]; 42 s64 ts __aligned(8); 43 } scan; 44 45 u8 data ____cacheline_aligned; 46 }; 47 48 #define MAX1118_CHANNEL(ch) \ 49 { \ 50 .type = IIO_VOLTAGE, \ 51 .indexed = 1, \ 52 .channel = (ch), \ 53 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 54 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 55 .scan_index = ch, \ 56 .scan_type = { \ 57 .sign = 'u', \ 58 .realbits = 8, \ 59 .storagebits = 8, \ 60 }, \ 61 } 62 63 static const struct iio_chan_spec max1118_channels[] = { 64 MAX1118_CHANNEL(0), 65 MAX1118_CHANNEL(1), 66 IIO_CHAN_SOFT_TIMESTAMP(2), 67 }; 68 69 static int max1118_read(struct iio_dev *indio_dev, int channel) 70 { 71 struct max1118 *adc = iio_priv(indio_dev); 72 struct spi_transfer xfers[] = { 73 /* 74 * To select CH1 for conversion, CNVST pin must be brought high 75 * and low for a second time. 76 */ 77 { 78 .len = 0, 79 .delay = { /* > CNVST Low Time 100 ns */ 80 .value = 1, 81 .unit = SPI_DELAY_UNIT_USECS 82 }, 83 .cs_change = 1, 84 }, 85 /* 86 * The acquisition interval begins with the falling edge of 87 * CNVST. The total acquisition and conversion process takes 88 * <7.5us. 89 */ 90 { 91 .len = 0, 92 .delay = { 93 .value = 8, 94 .unit = SPI_DELAY_UNIT_USECS 95 }, 96 }, 97 { 98 .rx_buf = &adc->data, 99 .len = 1, 100 }, 101 }; 102 int ret; 103 104 if (channel == 0) 105 ret = spi_sync_transfer(adc->spi, xfers + 1, 2); 106 else 107 ret = spi_sync_transfer(adc->spi, xfers, 3); 108 109 if (ret) 110 return ret; 111 112 return adc->data; 113 } 114 115 static int max1118_get_vref_mV(struct iio_dev *indio_dev) 116 { 117 struct max1118 *adc = iio_priv(indio_dev); 118 const struct spi_device_id *id = spi_get_device_id(adc->spi); 119 int vref_uV; 120 121 switch (id->driver_data) { 122 case max1117: 123 return 2048; 124 case max1119: 125 return 4096; 126 case max1118: 127 vref_uV = regulator_get_voltage(adc->reg); 128 if (vref_uV < 0) 129 return vref_uV; 130 return vref_uV / 1000; 131 } 132 133 return -ENODEV; 134 } 135 136 static int max1118_read_raw(struct iio_dev *indio_dev, 137 struct iio_chan_spec const *chan, 138 int *val, int *val2, long mask) 139 { 140 struct max1118 *adc = iio_priv(indio_dev); 141 142 switch (mask) { 143 case IIO_CHAN_INFO_RAW: 144 mutex_lock(&adc->lock); 145 *val = max1118_read(indio_dev, chan->channel); 146 mutex_unlock(&adc->lock); 147 if (*val < 0) 148 return *val; 149 150 return IIO_VAL_INT; 151 case IIO_CHAN_INFO_SCALE: 152 *val = max1118_get_vref_mV(indio_dev); 153 if (*val < 0) 154 return *val; 155 *val2 = 8; 156 157 return IIO_VAL_FRACTIONAL_LOG2; 158 } 159 160 return -EINVAL; 161 } 162 163 static const struct iio_info max1118_info = { 164 .read_raw = max1118_read_raw, 165 }; 166 167 static irqreturn_t max1118_trigger_handler(int irq, void *p) 168 { 169 struct iio_poll_func *pf = p; 170 struct iio_dev *indio_dev = pf->indio_dev; 171 struct max1118 *adc = iio_priv(indio_dev); 172 int scan_index; 173 int i = 0; 174 175 mutex_lock(&adc->lock); 176 177 for_each_set_bit(scan_index, indio_dev->active_scan_mask, 178 indio_dev->masklength) { 179 const struct iio_chan_spec *scan_chan = 180 &indio_dev->channels[scan_index]; 181 int ret = max1118_read(indio_dev, scan_chan->channel); 182 183 if (ret < 0) { 184 dev_warn(&adc->spi->dev, 185 "failed to get conversion data\n"); 186 goto out; 187 } 188 189 adc->scan.channels[i] = ret; 190 i++; 191 } 192 iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan, 193 iio_get_time_ns(indio_dev)); 194 out: 195 mutex_unlock(&adc->lock); 196 197 iio_trigger_notify_done(indio_dev->trig); 198 199 return IRQ_HANDLED; 200 } 201 202 static void max1118_reg_disable(void *reg) 203 { 204 regulator_disable(reg); 205 } 206 207 static int max1118_probe(struct spi_device *spi) 208 { 209 struct iio_dev *indio_dev; 210 struct max1118 *adc; 211 const struct spi_device_id *id = spi_get_device_id(spi); 212 int ret; 213 214 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); 215 if (!indio_dev) 216 return -ENOMEM; 217 218 adc = iio_priv(indio_dev); 219 adc->spi = spi; 220 mutex_init(&adc->lock); 221 222 if (id->driver_data == max1118) { 223 adc->reg = devm_regulator_get(&spi->dev, "vref"); 224 if (IS_ERR(adc->reg)) 225 return dev_err_probe(&spi->dev, PTR_ERR(adc->reg), 226 "failed to get vref regulator\n"); 227 ret = regulator_enable(adc->reg); 228 if (ret) 229 return ret; 230 231 ret = devm_add_action_or_reset(&spi->dev, max1118_reg_disable, 232 adc->reg); 233 if (ret) 234 return ret; 235 236 } 237 238 indio_dev->name = spi_get_device_id(spi)->name; 239 indio_dev->info = &max1118_info; 240 indio_dev->modes = INDIO_DIRECT_MODE; 241 indio_dev->channels = max1118_channels; 242 indio_dev->num_channels = ARRAY_SIZE(max1118_channels); 243 244 /* 245 * To reinitiate a conversion on CH0, it is necessary to allow for a 246 * conversion to be complete and all of the data to be read out. Once 247 * a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go 248 * into AutoShutdown mode until the next conversion is initiated. 249 */ 250 max1118_read(indio_dev, 0); 251 252 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL, 253 max1118_trigger_handler, NULL); 254 if (ret) 255 return ret; 256 257 return devm_iio_device_register(&spi->dev, indio_dev); 258 } 259 260 static const struct spi_device_id max1118_id[] = { 261 { "max1117", max1117 }, 262 { "max1118", max1118 }, 263 { "max1119", max1119 }, 264 {} 265 }; 266 MODULE_DEVICE_TABLE(spi, max1118_id); 267 268 static const struct of_device_id max1118_dt_ids[] = { 269 { .compatible = "maxim,max1117" }, 270 { .compatible = "maxim,max1118" }, 271 { .compatible = "maxim,max1119" }, 272 {}, 273 }; 274 MODULE_DEVICE_TABLE(of, max1118_dt_ids); 275 276 static struct spi_driver max1118_spi_driver = { 277 .driver = { 278 .name = "max1118", 279 .of_match_table = max1118_dt_ids, 280 }, 281 .probe = max1118_probe, 282 .id_table = max1118_id, 283 }; 284 module_spi_driver(max1118_spi_driver); 285 286 MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>"); 287 MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver"); 288 MODULE_LICENSE("GPL v2"); 289